How to Fix Poor Drainage in a Flower Bed

Organic matter improves the texture of the soil and promotes good drainage.

Slow-draining soil holds too much water, keeping the roots of plants wet for prolonged periods. Wet roots are not able to absorb the oxygen needed for plant growth. As a result, plants die or develop root rot, which eventually kills the plant. Improving drainage allows roots to breathe while still providing enough water for healthy growth. Amending the soil to improve its texture promotes good drainage and increases aeration to the roots.

Things You'll Need

• Garden spade
• Ruler
• Watch
• Organic soil amendments
• Garden tiller
• Garden hoe
• Trowel
• Garden rake

Instructions

1. Determine how well your soil drains before you amend the soil. Dig a hole 12 inches deep and about 12 inches in diameter.

2. Fill the hole with water and allow it to drain completely. Refill the hole and measure the depth of the water in inches.

3. Check the water level in 15 minutes and measure the drop in the water level with a ruler.

4. Multiply this number by four to find out how much water drains in one hour. One to 6 inches an hour falls within the ideal range for most plants. If your soil drains less than 1 inch per hour it drains poorly and requires amending to improve drainage.

5. Amend poorly draining soil with organic material by spreading a 2- to 4-inch layer of compost, well-rotted manure or peat moss over the gardening area. Although peat moss is an excellent source of organic matter, it may also lower the pH. If you use peat moss, a soil test is recommended before planting.

6. Till the organic matter into the top 6 inches of the soil with a garden tiller. For small areas, amendments can be worked into the soil with a hoe or trowel.

7. Rake the area smooth with a garden rake. Plant seeds or seedlings following their recommended depth and spacing.

Tips & Warnings

• When calculating the rate of drainage, convert fractions of an inch to decimals; for example, 1/4 inch equals 0.25, 1/2 inch equals 0.50 and 3/4 inch equals 0.75.

References

• University of Rhode Island: Improving Soils for Vegetable Gardens
• Ohio State University: Improving Soils for Vegetable Gardening
• Colorado State University: Soil Drainage
• Cornell University: Soil Basics

Resources

• Oregon State University: Improving Garden Soil